&nbsp;SVG spec (<a href="http://www.w3.org/TR/SVG11/filters.html#feDisplacementMap">http://www.w3.org/TR/SVG11/filters.html#feDisplacementMap</a>) states that pixel values must be alpha-demultiplied before processing this filter operation.
<br>The following code does it, but when we DON&#39;T do it, output is more similar to output from Batik.<br><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if (map-&gt;mode == NR_PIXBLOCK_MODE_R8G8B8A8P){<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; alpha = (unsigned int) map_data[4*((x-x0) + width*(y-y0)) + 3];
<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if (alpha==0){<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; coordx = x-x0;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; coordy = y-y0;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; } else {<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; coordx = x-x0 + scale * ( ((double)NR_DEMUL_111( (unsigned int)map_data[4*((x-x0) + width*(y-y0)) + Xchannel], alpha))/255 - 
0.5 );<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; coordy = y-y0 + scale * ( ((double)NR_DEMUL_111( (unsigned int)map_data[4*((x-x0) + width*(y-y0)) + Ychannel], alpha))/255 - 0.5 );<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }<br><br><br>
Batik output:<br>
&nbsp;<a href="http://bighead.poli.usp.br/~juca/code/inkscape/batik-fed02.png">http://bighead.poli.usp.br/~juca/code/inkscape/batik-fed02.png</a><br>
Inkscape output without demultiplication:<br>
&nbsp;<a href="http://bighead.poli.usp.br/~juca/code/inkscape/displacement-map-test.png">http://bighead.poli.usp.br/~juca/code/inkscape/displacement-map-test.png</a><br>&nbsp;
<br>There is also this other bug that can be seen in the above screenshot: the lower and the right portions are not rendered, I dont know why.<br><br>JucaBlues<br>